U.S. patent number 4,796,952 [Application Number 07/050,862] was granted by the patent office on 1989-01-10 for chair with hinged backrest.
Invention is credited to Giancarlo Piretti.
United States Patent |
4,796,952 |
Piretti |
January 10, 1989 |
**Please see images for:
( Certificate of Correction ) ( Reexamination Certificate
) ** |
Chair with hinged backrest
Abstract
The chair is provided with a seat connected to a support
structure of the chair by means of one or more hinged
parallelograms consisting of pairs of tie-rods hinged to the seat
and to the support structure. The structure of the chair backrest
is integral with at least one of the tie-rods so as to allow the
seat to be raised when the backrest is pushed backwards. Provision
is also made for elastic means which are designed to counteract the
backwards movement of the backrest.
Inventors: |
Piretti; Giancarlo (Bologna,
IT) |
Family
ID: |
11283420 |
Appl.
No.: |
07/050,862 |
Filed: |
May 18, 1987 |
Foreign Application Priority Data
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Jun 12, 1986 [IT] |
|
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53523/86[U] |
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Current U.S.
Class: |
297/300.5;
297/316; 297/340 |
Current CPC
Class: |
A47C
1/03272 (20130101) |
Current International
Class: |
A47C
1/032 (20060101); A47C 1/031 (20060101); A47C
003/20 () |
Field of
Search: |
;297/300,316,320,321,340,341 ;248/157,421 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Dorner; Kenneth J.
Assistant Examiner: Brown; Peter R.
Attorney, Agent or Firm: Fuller, Puerner & Hohenfeldt,
S.C.
Claims
I claim:
1. A chair comprising a support structure; a seat connected to the
support structure by means of a pair of first and second levers
having respective first ends hinged to the seat and respective
second ends hinged to the support structure, so that the support
structure, first and second levers, and seat define a parallelogram
system that is able to move the seat between a lowered position and
a raised position; and a backrest hinged to the support structure
and operationally connected to the seat so as to be able to pivot
between an upright position corresponding to the lowered position
of the seat and a reclined position corresponding to the raised
position of the seat,
characterized in that:
a. the backrest (20) is integral with at least one of the second
levers (27);
b. elastic means (42) are associated with the parallelogram system
(18, 19, 25, 27) and are designed to hold the backrest (20)
elastically in the upright position (A);
c. at least one of the levers (27) has, on the end hinged to the
support structure (12), an arm (27b) such that the arm defines with
the lever (27) a right-angled lever pivotally mounted on the
support structure (12), the elastic means (42) being inserted
between the arm (27b) and the support structure (12);
d. a rod (31) is hinged to the arm (27b) of the right-angled lever,
which rod is provided with an annular shoulder (31a) facing an
associated projection (40) integral with the support structure
(12), the elastic means comprises a helical spring (42) coaxial
with the rod (31) being arranged between the shoulder (31a) and the
projection (40) to render the parallelogram system adjustable.
2. The chair according to claim 1, characterized in that each lever
of the adjustable parallelogram system comprises an arm to form
first and second right-angled levers (25, 27), to the respective
arms (25b, 27b) of the right-angled levers the ends of the rod (31)
are hinged.
3. The chair according to claim 1 or claim 2 in which the support
structure (12) comprises a pair of longitudinal braces (18) in the
vicinity of the seat (19), and
characterized in that:
a. the pairs of first and second levers comprise a first pair (25)
and a second pair (27) of right-angled levers hinged on the braces
(18), the second pair of right-angled levers being hinged close to
the backrest (20);
b. the backrest (20) includes an internal tubular structure
(21);
c. the second pair of levers are provided with portions (27c) to
which the backrest internal structure is fixed;
d. each lever of the first and second pairs of right-angled levers
has a respective first arm (25a, 27a) hinged to the seat (19) and a
respective second arm (25b, 27b); and
e. the rid is hinged to the second arms of the respective
levers.
4. The chair according to claim 3, characterized in that the
longitudinal braces (18) comprise U-shaped metal sections inside
which the rods (31) and the helical springs (42) are contained.
5. The chair of claim 4 characterized in that:
a. the rod comprises a center section and two end sections;
b. the annular shoulder is formed on the rod center section;
c. the support structure projection is fabricated with a fork shape
that defines a space adapted to accept the rod center section for
reciprocation within the forked space; and
d. the helical spring is coaxial with the rod center section.
6. The chair according to claim 5 characterized in that the rod end
sections are hinged to the second arms of the respective right
angled levers at locations proximate the longitudinal braces (18)
to thereby enable the parallelogram system to achieve a low
vertical profile.
7. A chair comprising:
a support structure,
a seat,
at least one front and one rear lever having respective opposed
ends that are pivotally connected to the support structure and the
seat, respectively, so as to define with the seat and support
structure a parallelogram linkage connecting the seat to the
support structure and allowing the seat to be moved between a
lowered position and a raised position,
a backrest support structure which is rigidly and non-pivotally
connected to said rear lever so as to be movable together with said
rear lever between an upright position corresponding to the lowered
position of the seat and the reclined position corresponding to the
raised position of the seat, and
spring means associated with at least one of said front and rear
levers for biasing the backrest support structure towards its
upright position corresponding to the lowered position of the
seat.
8. A chair as set forth in claim 7 wherein at least one of said
front and rear levers includes an arm, said spring means being
interposed between said arm and the support structure.
9. A chair as set forth in claim 8 wherein a rod is hinged to said
arm, said rod being provided with a shoulder facing an associated
projection integral with the support structure, and wherein a
helical spring coaxial with the rod is arranged between the
shoulder and the projection.
10. A chair as set forth in claim 9 wherein each of said front and
rear levers includes a respective arm, said rod having its ends
pivotally connected to said respective arms.
11. A chair as set forth in claim 10 wherein the support structure
includes a pair of longitudinal side braces adjacent the seat, each
of said braces pivotally supporting a front and a rear pair of
right-angled levers adjacent the front and the rear ends of the
longitudinal brace, respectively, each right-angled lever including
a first portion constituting the respective front and rear levers
and a second portion constituting the associated arm, the
right-angled levers of the rear pair further including portions
that are rigidly fixed to the backrest support structure.
12. A chair as set forth in claim 11 wherein said longitudinal
braces comprise U-shaped sections wherein said rod and said spring
means are located.
13. A chair as set forth in claim 12 wherein the seat is provided
with two longitudinal bars, each bar having two inverted U-shaped
brackets rigidly fixed to the front and the rear ends thereof, each
bracket being pivotally connected to a corresponding pair of said
right-angled levers.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates to a chair comprising a support
structure and a seat connected to the support structure by means of
an adjustable parallelogram system that includes members in the
form of levers. The first ends of the levers are hinged to the
seat, and the second ends of the levers are hinged to the support
structure such that the seat is able to move between a lowered
position and a raised position. A backrest is hinged to the support
structure and is operationally connected to the seat so as to be
able to pivot between an upright position corresponding to the
lowered position of the seat and a reclined position corresponding
to the raised position of the seat.
2. Description of the Prior Art
French Pat. No. 2,045,120 discloses a chair having a parallelogram
system for pivotally supporting a seat on a support structure. The
backrest is pivoted to the support structure by a lever that is not
part of the seat supporting parallelogram system. Reclining the
backrest causes the lever to force the back edge of the seat
upwardly and backwardly relative to the support structure. The
chair of the aforementioned patent allows the backrest to exert on
the back of the user a force proportional to his weight. However,
the structure of the chair of the French patent is somewhat
complicated. Moreover, the design of the adjustable parallelogram
system associated with the mechanism for controlling displacement
of the seat by the backrest requires excessive space.
SUMMARY OF THE INVENTION
The air of the present invention is to provide a chair equipped
with a seat/backrest connecting system which is particularly simple
and compact, and which does not possess the drawbacks of the
solutions previously adopted.
According to the invention, this aim is achieved by designing the
backrest to be integral with one of the levers, and by providing
elastic means which are associated with the adjustable
parallelogram system and designed to hold the backrest elastically
in the upright position.
As a result of the above mentioned characteristic features, the
adjustable parallelogram system has particularly small dimensions,
allowing it to be used even in so-called stackable chairs.
Furthermore, because of the compactness of the backrest/seat
connecting system, it is possible to obtain a chair which is both
aesthetic and offers the same features as a chair or arm chair
which is considerably more complex, costly, and larger in size.
Preferably, in the chair according to the invention, at least one
of the levers has, on the end that is hinged to the support
structure, an arm such that the arm defines, together with the
lever itself, a first right angle lever that is pivotally mounted
on the support structure, with the elastic means being inserted
between the arm and the support structure.
Further characteristic features and advantages of the chair
according to the invention will emerge from the detailed
description provided by way of a non-limited example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a chair according to the invention;
FIG. 2 is a perspective view showing the adjustable parallelogram
system;
FIG. 3 is a cross sectional view taken along the line III--III of
FIG. 2, showing the configuration when the seat is lowered;
FIG. 4 is a view similar to FIG. 3, but showing the seat in the
raised position;
FIG. 5 is a cross sectional view taken along line V--V of FIG. 4;
and
FIG. 6 is a cross sectional view taken along line VI--VI of FIG.
4.
DETAILED DESCRIPTION OF THE INVENTION
Although the disclosure hereof is detailed and exact to enable
those skilled in the art to practice the invention, the physical
embodiments herein disclosed merely exemplify the invention which
may be embodied in other specific structure. The scope of the
invention is defined in the claims appended hereto.
With reference to the drawings, numeral 10 denotes in its entirety
a chair of the stackable type. The chair 10 comprises a support
structure 12 that includes front legs 13, rear legs 14, a front
tubular cross-piece 15 joining the front legs 13 at the tops
thereof, and a rear tubular cross-piece 16 joining the rear legs 14
at the tops thereof. A pair of U-shaped longitudinal braces 18 join
the front cross-piece 15 and the rear cross-piece 16.
The chair 10 also has a seat 19 and a backrest 20. The backrest 20
is provided with an internal structure including metal tubes
21.
Each brace 18 has, at the front, a first pair of lugs 22, and at
the rear, a second pair of lugs 23 adjacent the rear cross-piece 16
of the chair 10. A first pair of right-angled levers 25 is hinged
at 24 to the first pair of lugs 22. A second pair of right-angled
levers 27 is hinged at 26 to the second pair of lugs 23. Each first
right-angled lever 25 has a first end 25a hinged at 29 to the seat
19 and a second end 25b hinged at 30 to a metal rod 31.
In exactly the same way, each right-angled lever 27 has a first end
27a hinged at 32 to the seat 19 and a second end 27b hinged at 33
to the metal rod 31. The first ends 25a and 27a of the first and
second right-angle levers 25 and 27, respectively, are hinged to
the seat 19 by inserting U-shaped metal members 50 and 51 between
the pairs of levers 25 and 27, respectively. The bases of the
U-shaped members 50 and 51 are fixed at 52 and 53 to the ends of a
metal bar 34. The bar 34 has openings 35 for connecting it, by
means of screws 36, to the seat 19.
Each right-angle lever 27 has, in the vicinity of the point 26
where it is hinged to the longitudinal brace 18, a portion 27c
which is welded to the metal structure 21 of the backrest 20. Each
lever 27 also has a stop portion 27d located in the vicinity of the
end 27b. The stop portion 27d is designed to abut against the
bottom wall of the brace 18.
The rod 31, which is hinged to the second ends 25b and 27b of the
right-angled levers 25 and 27, respectively, has an annular
shoulder 31a facing a projection 40 which is substantially
fork-shaped and integral with the walls of the longitudinal brace
18. The rod 31 is slidably mounted inside the projection 40.
Between the projection 40 and the annular shoulder 31a is located a
helical spring 42 which is coaxial with the rod 31. The mode of
operation of the spring 42 will be explained below.
FIG. 3 shows the "rest" condition of the chair wherein the backrest
20 assumes an upright position indicated by A. In this condition,
the spring 42 acts on the adjustable parallelogram comprised of the
longitudinal brace 18, the seat 19, and the arms of the levers 25
and 27 located between the hinge points 24 and 29 and the hinge
points 26 and 32, respectively, so as to keep the seat 19 in the
lowered position, indicated by B, wherein the stop portions 27d of
the levers 27 are in contact with the respective braces 18.
In the operative condition, i.e., when the user presses with
his/her back against the backrest 20, the latter pivots backwards
into a reclined stable position, indicated by C. At the same time,
because of the metal structure 21 being fixed to the second
right-angled levers 27, the seat 19 is raised, due to the rotation
of the right-angled levers 25 and 27 about their respective
fulcrums 24 and 26, until the stable condition indicated by D in
the drawings is reached. This stable condition is shown in detail
in FIG. 4. Because of the parallelogram system for supporting the
seat, the plane of the seat in the raised condition D is
substantially parallel to the plane of the seat in the lowered
condition B.
In the stable condition C, the backrest 20 exerts on the back of
the user a force proportional to the weight of the user, further
increased by the force due to the helical spring 42. In this way,
it is possible to minimize the dimensions of the levers 25 and 27
and hence the entire adjustable parallelogram system, thereby
ensuring reliable and comfortable operation for the user.
The present invention is intended to be applicable to all devices
which perform the same functions, using the same innovative idea.
For example, the seat/backrest connecting system may be
advantageously used for any type of chair or arm chair.
* * * * *